CLYDE SEA AREA. 645 



for purposes of calculation in the Loch Strivan Basin, the remainder is reckoned in 

 the Dunoon Basin. 



Dunoon Basin, 47 square miles in area between coast lines, and averaging 20 

 fathoms in depth, contains a straight narrow trough with an axial mean depth of 

 39 fathoms, w T hich runs from near the north eud of Great Cumbrae for 20 miles due 

 north up " Loch Long " to the junction with Loch Goil. At first the depression keeps 

 close to the east shore (Renfrewshire) under the hilly uplands which there approach 

 the sea, then it crosses to the west side where the deepest part (56 fathoms) is 

 found just to the south of Gantock Beacon, opposite Dunoon. Another depression 

 marks the end of the trough off Dog Rock at the extremity of the mountainous 

 peninsula known as Argyll's Bowling-Green, where Loch Goil and Loch Long meet. 

 Section 6, Plate VI L, shows the profile along the axis of greatest depth for the Dunoon 

 Basin and Loch Long. The southern part of this basin communicates with the north- 

 eastern branch of the Arran Basin across Bute Plateau, the northern part runs under 

 a steep and lofty line of hills on the west side. Besides innumerable torrents which 

 bring down the rainfall after every shower, Dunoon Basin receives through the shallow 

 indentation of the Holy Loch the fresh water drainage from Loch Eck, which occupies 

 a narrow inland valley. The land draining into the Dunoon Basin measures 86 square 

 miles, and is mainly on the eastern side. The whole volume of water it contains at low 

 tide is 075 cubic sea miles, with an addition of 0*05 at high tide. 



The Clyde Estuary joins Dunoon Basin about the middle ; the line of demarcation 

 may be taken as that joining Cloch Point and Baron Point. For 4 miles eastward the 

 estuary has a width of about 2-g miles, and the depth of water decreases gradually until 

 between Greenock and Roseneath Point, where the mouth of the Gareloch suddenly 

 doubles its width, and it shoals abruptly to 5 fathoms. From this position eastward for 

 10 miles to Bowling the estuary is very shallow, full of sandbanks, and diminishes 

 steadily in width. But for the bold front of the Kilpatrick Hills, along a short stretch of 

 the bank east of Dumbarton, the shores of the estuary are low and flat. The Leven at 

 Dumbarton carries in the overflow of Loch Lomond. The estuary up to Bowling has a 

 superficial area of 27 square miles, and, excluding the river Leven, receives, in addition 

 to the river Clyde, the drainage of 60 square miles of land. Loch Lomond, tributary to 

 the estuary, with its surface at a level 23 feet higher, belongs geographically to the 

 Clyde Sea Area, and a slight subsidence would admit sea water. The northern part of 

 this loch, with regard to its general trend, its narrow trough-like configuration under the 

 surface, and the steep, close mountain walls of crystalline rock which hem it in, is exactly 

 similar to the other fjords which wind amongst the Western Highlands.* It serves to 

 carry the overflow from a region of very high rainfall into the estuary. The area of 

 Loch Lomond, including its islands, is 28 square miles ; and no less than 267 square 

 miles of rugged land drain into it, mainly from the north and east. The navigable 

 channel of the Clyde, maintained by dredging from Port-Glasgow to Glasgow, is entirely 



* J. Y. Buchanan, "On the Distribution of Temperature in Loch Lomond," Proc. Roy. 8oc. Edin., vol. xiii. p. 403. 



